Weirdo Bore Size on 454

[shaun]

I got my block back from the machine shop a couple weeks back and while having a discussion with my dad he said he though the block was .030 over before i sent it in (he sent it in years back when it was going to go in his dulley). So i called up the machine shop and asked the guy what the bore size was and this was his responce 'it was .030 over well actually closer to .040 over'. I said ok and hung up the phone and though about it for a sec and though 'do they even make .040 over pistons?'. Well i searched around JE's catalog doesnt have .040 and i wasnt able to find anything. I called the machine shop today about it again and told him i've been hearing that if it's over .030 i need to go up to .060 and he asked why the bores where perfect. Well apparently we both where on the wrong page. I gave him the block thinking that if something was odd that he was gong to tell me what he though i should do. He though i was just cleaning up the block, getting it honed so that i can put the original pistons i took out of it back into it. He told me he was going to look thru his 'master piston catalog' tongiht and he'd give me a call back.
What is your guys opinions? can i even get .040 pistons? i'm looking for 10:1 compresson with a 118cc head (990's). He quoted me 225 to bore it over to .060 at this point i'm probably going to go else where.

[Fiat48]

There are shelf pistons that are .040 over but they are usually not performance pistons. You can get near any size you want in a performance forged piston but you will be charged extra for "odd" sizes. .030 & .060 are common sizes.
I think you need to go down to that machine shop and have him measure the bore for you. Sounds like some confusion in phone conversations. I seriously doubt the bore is worn "near .040" .
And for what you are trying to do in compression, why not use a TRW forged piston. Good piston for 1/2 the price of JE.

[396_Z]

.040 is actually a common overbore as odd as it seems.

[VD CRUISER]

What size were the pistons you took out of it?

[shaun]

I havnt done any measuring yet because i dont have a caliper yet. The block was rebuilt 3 years ago by pepboys (dont ask me why it was done with them). My dad was working 12+ hour shifts at that time and didnt have the time to do a lot of the measuring that needed to be done so he droped the block off to them and they sent it out and it came back with the bottom end complete. I'm assuming the block was .030 over when pepbodys got it and they went another .010 (i dont see why they would have went from std bore to .040).
Fiat: does trw make a .040 over piston?

[Fiat48]

Yep. lots to chose from. Some in forged pistons and probably cast as well. Go here: http://www.flatlanderracing.com/trwchevy454.html

[Snowboat]

Shaun...........at the risk of sounding forward or offending, I think you need a mentor. Do you have someone near that is quite knowlegeable about engines? If not you might want to find one. Depending on your level of experience it can save you a lot of time, tears and money. You sound plenty smart but a hands on helper is hard to beat. You can get great advise on these boards, but its not the same as having someone close at hand. If you don't have a bud, ask about a dependable machinest in your area and getting the long block put together. Not enough room here, for me to list all of the machinery mistakes I have made, or been around. Good luck.

[shaun]

Fiat: after doing some calculations 4.290 x 4.290 x 4.00 x 6.2832 i came up with 462.54656448 and by looking at the size on that site i see only one set of forged pistons for a 463. I'm gussing they rounded 462.546 up to 463? This does not make any sense to me since it doesnt seam like you could round up. Am i reading this right or do i have somthing wrong?
Snowboat: my dad's built 2 engines by him self besides pit crewing for California Hustler/RWR/Spirit of America and ripping the fueler down and putting it back together between runs but he isnt what i would call a expert. He's just learned from what people have told him and showed him what to do. He will be helping me with the assembily. Putting the motor back together stock is a easy task for the most part, but getting my combination right for whati want and learning all these new performance type things is going to take me a while i'm sure. I've used this machinest before many times and he's a good guy, i think we just had a communication problem.

[Fiat48]

All you want to worry about is 4.290 bore size. The cubic inch deal you have figured right. Just some people round up the numbers and some down.
Check with that machinest in person. He should put in a dial bore gauge and show you the bore size and any taper, wear or out of round.

[shaun]

I'm not seeing a bore size on that site just the CID. I'm gonna take a better look around tomarrow and see what i can find. As for taking the block to him and getting the exact measurment i will do that.

[Bondo]

I don't know...... Maybe it's just me.......
But,
I've Always bought my pistons First........
Then had the block machined to match my Pistons,
Rather than trying to match pistons to a pre-bored Block...........:(
After all, there Are Design Tolerences,+ You'll not have the Actual Measurements, till Parts are In-Hand................

[Snowboat]

That's good that you have your Dad. With all the info available you'll be just fine. Before these boards I didn't have any way to ask about v drives, handling, hardware, or more extreme engines. Good luck.

[78Eliminator]

Shaun, I have a dial bore gauge and a mic set. How about lunch and I will come up there and measure it for you? You will have to wait till next weekend though.... Let me know.

[Fiat48]

Originally posted by Shaun
I'm not seeing a bore size on that site just the CID. I'm gonna take a better look around tomarrow and see what i can find. As for taking the block to him and getting the exact measurment i will do that.
Now I see what you are talking about. Standard bore size for a 454 is 4.250. The piston end number denotes the oversize. So part number L2377F40 means .040 oversize which would be 4.290. The F means forged piston. Maybe that will help.

[058]

Originally posted by Fiat48
Now I see what you are talking about. Standard bore size for a 454 is 4.250. The piston end number denotes the oversize. So part number L2377F40 means .040 oversize which would be 4.290. The F means flat top piston. Maybe that will help. I thought the "F" meant forged?

[Fiat48]

You're right 058. I corrected that it means forged.

[shaun]

Fiat: Looks like they only have one type of .040 over forged pistons.
78Eliminator: If you are you to it and dont mind comming down that would be great. I would offer to come up but i dont have a vehical right now that i can transport the block in (long story). I'll pm you with more details.